JP3863631B2 - Burner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention relates in the field of combustion technology to a double-cone type burner, which also supplies gaseous fuel before it flows into the burner chamber with respect to the flow of combustion air.
[0002]
[Prior art]
From European Patent No. 0321809, the basic structure of a double cone type burner which is the subject of the present invention is known. This known burner consists essentially of a hollow partial cone that complements each other to form a cone, and comprises a tangential air inlet slit and a supply of gaseous and liquid fuels. The central axis of the hollow partial cone has a cone angle (Kegelneigung) that expands in the flow direction, and is shifted from each other and extends in the vertical direction. A fuel nozzle is arranged on the burner head in a conical inner chamber formed by the partial cone. Gaseous fuel is supplied to the combustion air stream via a fuel injector disposed along the air inlet slit before the combustion air stream flows into the burner inner chamber. A fuel / air mixture is therefore generated in the immediate vicinity of the end of the tangential air entry slit. In the case of this known type, the air inflow plane and the gas inflow plane (hole plane) overlap each other.
[0003]
In connection with the sudden expansion of the cross section at the burner outlet, the swirl flow increases along the cone axis, creating a counterflow zone on the burner axis downstream of the burner outlet that stabilizes the flame. Is done. The flame is ignited for the first time at the stagnation point of this backflow area.
[0004]
The last multiple fuel injector along the air inlet slit is very close to the burner outlet and thus close to the flame in the known type. In these places, therefore, the length of the premixing section is extremely short, so that the fuel injected from the fuel injector located downstream is poorly mixed with air. Due to poor mixing of fuel and air, a rich mixture region is generated locally, which raises the flame temperature and thus raises the NOx value. In addition, the additional load on the burner front at these locations causes overheating and the burner front material must be protected with an expensive zircon coating.
[0005]
To extend the premixing section along the burner axis and reduce NOx emissions, a complex transition piece is required between the burner and the post member, eg, a tube placed in front of the combustion chamber. is there. The flow area generated by the burner downstream causes problems with the axial velocity at the edge or center of the post member. As a result, backfire occurs and the burner cannot be operated.
[0006]
[Problems to be solved by the invention]
The present invention seeks to eliminate all of the above disadvantages. The problem underlying the present invention is to produce a double cone type burner as follows. That is, with a simple structure, it can be manufactured inexpensively, and fuel from the downstream fuel injector located downstream can be better premixed with combustion air, thereby reducing NOx emissions compared to the prior art. Furthermore, it is a burner that does not require an expensive special coating by further reducing the heat load on the burner front.
[0007]
[Means for Solving the Problems]
Enlargement object is achieved in the present invention is a burner for burning liquid fuel and gaseous fuel, which consists of a hollow of the two sectional bodies forming a single cone I Oh complement each other, in the flow direction The central axes of two partial cones having a conical angle are shifted in a direction orthogonal to the central axis and in a direction of shearing the partial cones, and by shifting each central axis, two gaps are formed along the edge, to flow into the combustion air tangentially, air inlet plane by plane including the respective central axes which are offset are specified, the supply for gaseous fuel are arranged, in the burner head conical inner chamber formed by the partial conical bodies, fuel nozzle for liquid fuel is arranged, the supply for gaseous fuel, outside of each partial cone edge In those Tei Ru format comprising a plurality of fuel injectors, by stretching the outer end of each sectional cone body in the circumferential direction, Yes in the sectional bodies were part batchwise superimposed, the central axes of the partial conical bodies In the cross section orthogonal to the cross section, the straight line formed by the crossing of the cross section and the air inflow plane intersects with the straight line connecting the two corresponding fuel injectors provided at the outer end portions of the respective partial cones. The defined overlapping angle increases in the burner flow direction, and at the same time, the distance between the fuel injector and the air inflow plane into the burner increases as the overlapping angle increases. Therefore, the fuel injection plane and the air inflow plane no longer overlap each other, and the fuel injection plane changes its position with respect to the air inflow plane along the burner.
[0008]
【The invention's effect】
Among the advantages of the present invention are the following. That is, in the area of the fuel injector located downstream, the premixing section is extended to improve the premixing of the gaseous fuel and the combustion air, and as a result, the NOx emission and the burner front heat load are reduced. In addition, the burner stabilizes the flame position and reduces pulsation.
[0009]
Advantageously, the overlap angle is 0 ° at the apex of the cone and continuously increases to the burner front, with a maximum overlap angle of 90 °.
[0010]
By avoiding overlapping of the partial cones at the apex of the cone, a high axial velocity is obtained on the symmetry axis inside the burner, as in the prior art.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on the embodiment shown in FIGS.
[0012]
In the drawing, an embodiment according to the invention of a burner formed by two partial cones is shown. In the drawings, only those elements that are important to an understanding of the present invention are shown. Different media flow directions are indicated by arrows. FIG. 1 is a perspective view of a burner according to the present invention. For ease of understanding, the sectional views of FIGS. 2 to 4 may be referred to simultaneously with FIG.
[0013]
The burner of FIG. 1 consists of two partial cones 1 and 2 that are offset and superposed. By shifting the central axes of the partial cones 1 and 2 from each other, one air inflow slit 5 and 6 in the tangential direction is formed on both sides in a mirror image arrangement. The combustion air 7 reaches the inner chamber 8 of the burner through these air inflow slits 5 and 6. Both partial cones 1, 2 each have a cylindrical starting end 9, 10, which likewise extend out of phase with each other and therefore also tangential to the area. Air inflow slits 5 and 6 are formed. The cylindrical start ends 9 and 10 accommodate a nozzle 11 for spraying the liquid fuel 12. The burner may be constructed without a cylindrical starting end 9, 10, i.e. a pure conical shape. In this case, the fuel nozzle 11 is directly accommodated at the tip of the cone. Both partial cones 1, 2 each have one supply, ie fuel pipes 13, 14, the openings 15 of these fuel pipes forming a fuel injector. Via the fuel injector 15, gaseous fuel is mixed into the combustion air 7 which flows in through the tangential air inlet slits 5, 6.
[0014]
The burner is provided with a front plate 18 which serves as a fixing part for the partial cones 1 and 2 on the side of the combustion chamber 17, and the front plate 18 has a number of holes 19, through these holes, If necessary, dilution air or cooling air 20 is supplied to the front of the combustion chamber 17 or the combustion chamber wall.
[0015]
When the liquid fuel 12 is used for the operation of the burner, the liquid fuel flows through the fuel nozzle 11 and is injected into the burner inner chamber 17 at an acute angle, thereby producing a homogeneous fuel spray. A conical liquid fuel profile (Fluessigbrennstoffprofil) 23 is surrounded by a combustion air stream 7 which flows in and swirls in a tangential direction. The concentration of the liquid fuel 12 is continuously reduced in the axial direction by the mixed combustion air 7. The optimum fuel concentration over the cross section is achieved in the region of vortex breakdown, ie in the region of the backflow zone 24. Ignition takes place at the tip of the backflow area 24. Only at this point is a stable flame front 25 produced. Flame stability is obtained by increasing the swirl number in the flow direction along the cone axis. As a result, flashback inside the burner no longer occurs.
[0016]
During combustion of the gaseous fuel 16, an air-fuel mixture with the combustion air 7 is generated in the air inflow slits 5 and 6. In accordance with the present invention, both partial cones 1, 2 are partially overlapped with each other and the overlap angle δ is 0 ° at the apex of the cone (ie no overlap occurs at the apex), then The overlapping angle δ gradually increases in the flow direction to the burner outlet, that is, to the front plate 18. The maximum overlapping angle δ is 90 °.
[0017]
When the overlapping angle is 0 ° at the tip of the cones of both the partial cones 1 and 2 or the cylindrical start ends 9 and 10, that is, when both partial cones do not overlap in the region, This further provides the advantage that a high axial velocity can be achieved in the burner on the axis of symmetry. A passage for the combustion air flow 7 is formed by the overlapping wall portions of the partial cones 1 and 2.
[0018]
The fuel injector 15 is also shifted in the upstream direction to the same extent as the overlapping angle δ changes. Thereby, the air inflow plane 21 and the fuel injection plane 22 no longer overlap each other. The fuel injection plane 22 changes its position with respect to the air inflow plane 21 along the burner in the direction toward the burner front, so that the premixing zone of each gaseous fuel 16 from each fuel injector to the air inflow plane 21 becomes gradually wider. ing.
[0019]
This achieves a homogeneous mixing of the gaseous fuel 16 and the combustion air 7, which lowers the flame temperature and thus reduces NOx emissions. Such a drop in flame temperature in the burner exit area reduces the heat load on the burner front material and otherwise eliminates the necessary zircon coating for the material.
[0020]
Furthermore, the flame occupies a more stable position as compared with the prior art in which the partial cones 1 and 2 are not overlapped with each other and the fuel injection plane 22 and the air inflow plane 21 are overlapped with each other. Burners according to the present invention tend to reduce pulsation as an additional advantage. The burner according to the present invention is very simple in construction (for example, no complicated transition piece for extending the premixing section is required) and is therefore inexpensive to manufacture.
[0021]
Of course, the present invention is not limited to the embodiments described above. The arrangement according to the invention can be used in the same way for burners consisting of more than two partial cones, for example so-called four-slit burners.
[Brief description of the drawings]
FIG. 1 is a perspective view of a double cone type burner.
FIG. 2 is a schematic cross-sectional view of a burner along the II-II plane of FIG.
3 is a schematic cross-sectional view of the burner along the III-III plane of FIG. 1. FIG.
4 is a schematic cross-sectional view of the burner along the IV-IV plane of FIG. 1;
[Explanation of symbols]
1, 2 Partial cone, 3, 4 Center axis, 5, 6 Air inflow slit, 7 Combustion air, 8 Burner inner chamber, 9, 10 Cylindrical start, 12 Liquid fuel, 13, 14 Fuel pipe, 15 Fuel Injector, 16 Gaseous fuel, 17 Combustion chamber, 18 Front plate, 19 Hole, 20 Diluted or cooled air, 21 Air inflow plane, 22 Fuel injection plane, 23 Liquid fuel profile, 24 Backflow area, 25 Flame front, δ Overlapping angle

Claims (2)

A burner for burning a liquid fuel (12) and the gaseous fuel (16), which consists of two parts cone hollow to form one of the cone I Oh complement each other (1,2), Each central axis (3, 4) of two partial cones (1, 2) having a conical angle expanding in the flow direction shears the partial cones in a direction perpendicular to the central axis (3,4). The combustion air is caused to flow in the tangential direction from the two gaps formed along the ends of the partial cones (1, 2) by shifting each central axis (3, 4). air inlet plane by plane including the respective central axes which are offset (3,4) are defined, the supply unit (13, 14) are arranged for the gaseous fuel (16), partial cones In the conical inner chamber (8) formed by (1,2) The fuel nozzle (11) for the liquid fuel (12) is arranged in the cylinder, and a supply unit for the gaseous fuel is provided with a plurality of fuels at the outer end of each partial cone (1, 2). in those forms Ru Tei with an injector (15), the outer end portion by stretching in the circumferential direction, overlapped portions cone body (1, 2) in part batchwise for each partial cone (1,2) In the cross section orthogonal to the central axis (3, 4) of each partial cone (1, 2), a straight line formed by intersecting the cross section and the air inflow plane, and each partial cone (1, 2) the overlap angle (δ) defined by the intersection of the two corresponding fuel injectors (15) provided at the outer end of the cross section increases in the burner flow direction, and at the same time, Fuel injector (15) and air inflow plane into the burner Burner, characterized in that the distance between the 21) increases with increasing angle ([delta]) superimposed.   The overlapping angle (δ) is 0 ° at the apex of the cone, continuously increasing toward the burner front (18) toward the downstream side, and the maximum overlapping angle (δ) is 90 °. The burner according to 1.

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